It is known that the L(S) configuration of certain 1,2,3,4-tetrahydroisoquinoline-3-carboxylic derivatives is required for improved biological activity for compounds possessing angiotensin-converting enzyme inhibitory activity as disclosed in U.S. Pat. No. 4,344,949. However, prior art synthesis techniques of chiral 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid intermediates have failed to produce compounds having acceptable levels of optical purity over 90% ee. The designation % ee (enantiomeric excess) represents: (% desired isomer--undesired isomer)/% total compound.